Image uploads blocked by Cloudflare - eviltoast

When I attempt to upload images to lemmy.world via the desktop web UI, I get the following error message:

SyntaxError: JSON.parse: unexpected character at line 1 column 1 of the JSON data

Looking at network traffic in dev tools, I see that I’m getting a 403 page from Cloudflare saying:

Sorry, you have been blocked You are unable to access lemmy.world Why have I been blocked? This website is using a security service to protect itself from online attacks…

I also get error messages when trying to upload images using Connect and Sync on an Android device. I successfully uploaded images in the past.